Tens of thousands of people use computer-based brain-training exercises to boost memory and mental fitness. These people will be disappointed to learn that a recently published study suggests the tools may not work.

In the 6-week study, Jessica Grahn and colleagues at the Medical and Research Council’s Cognition and Brain Sciences Unit in Cambridge, England randomized 11,430 healthy participants to one of 3 groups. The first engaged in online games designed to improve general intelligence skills like problem-solving and reasoning. The second group performed exercises aimed at increasing attention, short-term memory and mathematical skills—the focus of commercial brain-training programs. The control group browsed the Internet in search of answers to general knowledge questions.

Participants performed these activities for at least 10 minutes, 3-times each day.

Grahn’s team found that participants in the brain-training (second) group improved in the tasks that they practiced, but their improvement was about the same as that made by the control group. No groups showed improved cognitive skills that weren’t specifically targeted in their tasks.

The brain training industry is focused for the moment on software offerings and online programs. It generated $265 million in North American revenues last year, up from $225 in 2008. About 40% of these revenues came from consumers. The remaining came from schools and retirement communities.

Industry spokespeople said the study was flawed. “It’s not brain training,” Alvaro Fernandez, CEO of SharpBrains told the Wall Street Journal. Cognitive improvements can only be expected, he said, “after more than 15 hours of training and where each session lasts at least 30 minutes.”

Steven Aldrich, CEO of Posit Science, a brain-training vendor, added that the “study overreaches in generalizing that since their methods did not work, all methods would not work.”